The invention relates to particle separation and detection apparatus. Apparatus embodying the invention, and to be described below by way of example only, is for detecting oil mist, such as may arise under fault conditions in internal combustion engines and which may present a fire or explosion hazard. However, apparatus embodying the invention may be used for many other applications.
According to the invention, there is provided particle detecting apparatus for detecting the presence of particles in gaseous fluid, comprising light sensing means positioned to have a field of view extending axially along a sensing chamber defined by wall means extending from the light sensing means to an open end for receipt of the gaseous fluid, and at least two light emitters mounted to direct emitted light across the chamber in opposite directions along a common light path towards a sensing volume positioned on the axis of the chamber, whereby particles carried by the gaseous fluid into the sampling volume scatter some of the light therein for detection by the light sensing means.
According to the invention, there is further provided apparatus for detecting particles within gaseous fluid, comprising a measuring chamber for receiving the gaseous fluid, light emitting means mounted to direct light into the measuring chamber, and light detecting means having a field of view extending in the chamber and mounted to produce an output in response to the effect of particles in the gaseous fluid in the chamber on the light produced by the light emitting means, the light emitting means comprising at least two light emitter units positioned to direct light in opposite directions along a common light path across the chamber, each unit being switchable into a light detecting mode in which it responds to light received from the other along the said light path unit and produces a corresponding output, the output being dependent on contamination in the said light path.
According to the invention, there is also provided particle detecting apparatus for detecting the presence of particles within gaseous fluid, comprising: measuring means and gaseous fluid input/output means; the measuring means comprising a measuring chamber for receiving a sample of the gaseous fluid, light emitting means emitting light into the measuring chamber, and light detecting means operative to produce an output dependent on the effect of any particles in the gaseous fluid in the measuring chamber on the light emitted by the light emitting means; the gaseous fluid input/output means comprising a gaseous fluid inlet for receiving gaseous fluid from an area to be monitored and directing it into a receiving chamber, and an outlet through which gaseous fluid from the receiving chamber is exhausted; the measuring means being mounted within a first housing and the gaseous fluid input/output means being mounted in a second housing, the two housings being removably attached together such that gaseous fluid in the receiving chamber can enter the measuring chamber by diffusion.
According to the invention, there is yet further provided cyclone apparatus for removing at least some particulate matter from gaseous fluid carrying it, comprising inner and outer cylindrical walls arranged coaxially to define an annular passage, an inlet for the gaseous fluid into the annular chamber and an outlet therefrom, the inlet and outlet being spaced axially along the annular chamber, the inlet extending in a radial direction with respect to the annular chamber whereby gaseous fluid entering the chamber is directed in a generally circular direction around the annular chamber from the inlet to the outlet and the said particulate matter tends to be deposited at least on the outer wall of the annular chamber by centrifugal force.